US20060007772A1 - Non-volatile memory device - Google Patents

Non-volatile memory device Download PDF

Info

Publication number
US20060007772A1
US20060007772A1 US11/189,548 US18954805A US2006007772A1 US 20060007772 A1 US20060007772 A1 US 20060007772A1 US 18954805 A US18954805 A US 18954805A US 2006007772 A1 US2006007772 A1 US 2006007772A1
Authority
US
United States
Prior art keywords
gate
region
semiconductor device
voltage
substrate
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Abandoned
Application number
US11/189,548
Inventor
Kyu Choi
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
O2IC Inc
Original Assignee
O2IC Inc
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority claimed from US10/394,417 external-priority patent/US6965145B2/en
Application filed by O2IC Inc filed Critical O2IC Inc
Priority to US11/189,548 priority Critical patent/US20060007772A1/en
Assigned to O2IC, INC. reassignment O2IC, INC. ASSIGNMENT OF ASSIGNORS INTEREST (SEE DOCUMENT FOR DETAILS). Assignors: CHOI, KYU HYUN
Publication of US20060007772A1 publication Critical patent/US20060007772A1/en
Abandoned legal-status Critical Current

Links

Images

Classifications

    • GPHYSICS
    • G11INFORMATION STORAGE
    • G11CSTATIC STORES
    • G11C14/00Digital stores characterised by arrangements of cells having volatile and non-volatile storage properties for back-up when the power is down

Definitions

  • the present invention relates to semiconductor integrated circuits. More particularly, the invention provides a semiconductor memory that has integrated non-volatile and dynamic random access memory cells.
  • the invention has been applied to a single integrated circuit device in a memory application, there can be other alternatives, variations, and modifications.
  • the invention can be applied to embedded memory applications, including those with logic or micro circuits, and the like.
  • SRAM Static Random Access Memory
  • DRAM Dynamic Random Access Memory
  • SRAMs and DRAMs often include a multitude of memory cells disposed in a two dimensional array. Due to its larger memory cell size, an SRAM is typically more expensive to manufacture than a DRAM. An SRAM typically, however, has a smaller read access time and a lower power consumption than a DRAM. Therefore, where fast access to data or low power is needed, SRAMs are often used to store the data.
  • Non-volatile semiconductor memory devices are also well known.
  • a non-volatile semiconductor memory device such as flash Erasable Programmable Read Only Memory (Flash EPROM), Electrically Erasable Programmable Read Only Memory (EEPROM) or, Metal Nitride Oxide Semiconductor (MNOS), retains its charge even after the power applied thereto is turned off. Therefore, where loss of data due to power failure or termination is unacceptable, a non-volatile memory is used to store the data.
  • Flash EPROM flash Erasable Programmable Read Only Memory
  • EEPROM Electrically Erasable Programmable Read Only Memory
  • MNOS Metal Nitride Oxide Semiconductor
  • the non-volatile semiconductor memory is typically slower to operate than a volatile memory. Therefore, where fast store and retrieval of data is required, the non-volatile memory is not typically used. Furthermore, the non-volatile memory often requires a high voltage, e.g., 12 volts, to program or erase. Such high voltages may cause a number of disadvantages. The high voltage increases the power consumption and thus shortens the lifetime of the battery powering the memory. The high voltage may degrade the ability of the memory to retain its charges due to hot-electron injection. The high voltage may cause the memory cells to be over-erased during erase cycles. Cell over-erase results in faulty readout of data stored in the memory cells.
  • a high voltage e.g. 12 volts
  • FIG. 1 is a transistor schematic diagram of a prior art non-volatile DRAM 10 .
  • Non-volatile DRAM 10 includes transistors 12 , 14 , 16 and EEPROM cell 18 .
  • the control gate and the drain of EEPROM cell 18 form the DRAM capacitor.
  • Transistors 12 and 14 are the DRAM transistors.
  • Transistor 16 is the mode selection transistor and thus selects between the EEPROM and the DRAM mode.
  • FIG. 2 is a transistor schematic diagram of a prior art non-volatile SRAM 40 .
  • Non-volatile SRAM 40 includes transistors 42 , 44 , 46 , 48 , 50 , 52 , 54 , 56 , resistors 58 , 60 and EEPROM memory cells 62 , 64 .
  • Transistors 48 , 50 , 52 , 54 and resistors 58 , 60 form a static RAM cell.
  • Transistors 42 , 44 , 46 , 56 are select transistors coupling EEPROM memory cells 62 and 64 to the supply voltage Vcc and the static RAM cell.
  • Transistors 48 and 54 couple the SRAM memory cell to the true and complement bitlines BL and BL.
  • EEPROM 18 of non-volatile DRAM cell 10 ( FIG. 1 ) and EEPROM 62 , 64 of non-volatile SRAM cell 40 ( FIG. 2 ) consume relatively large amount of current and thus shorten the battery life. Accordingly, a need continues to exist for a relatively small non-volatile memory device that, among other things, is adapted for use in a non-volatile SRAM or DRAM and consume less power than those known in the prior art.
  • a non-volatile memory device (hereinafter alternatively referred to device) includes a guiding gate that extends along a first portion of the device's channel length and a control gate that extends along a second portion of the device's channel length. The first and second portions of the channel length do not overlap.
  • the guiding gate which overlays the substrate above the channel region, is insulated from the semiconductor substrate in which the device is formed via an oxide layer.
  • the control gate which also overlays the substrate above the channel region, is insulated from the substrate via an oxide-nitride-oxide layer.
  • the thickness of the oxide layer formed above the guiding gate is greater than the thickness of the oxide layer formed above the control gate. In other embodiments, the thickness of the oxide layer formed above the control gate is greater than the thickness of the oxide layer formed above the guiding gate.
  • the device includes five terminals, namely a source terminal coupled to the device's source region, a drain terminal coupled to the device's drain region, a guiding gate terminal coupled to the device's guiding gate, a control gate terminal coupled to the device's control gate, and a substrate terminal coupled to the semiconductor substrate in which the device is formed.
  • a first voltage is applied between the control gate terminal and the substrate terminal, a second voltage is applied between the guiding gate terminal and the substrate terminal, and a third voltage is applied between the drain and source terminals.
  • the application of these voltages causes two non-overlapping channel regions to be formed in the substrate. Subsequently, a channel connecting the source to drain region is formed in the substrate.
  • the electrons tunnel through or are injected in the oxide layer and are trapped in the nitride layer due to hot electron injection. The injected electrons remain trapped in the nitride layer even after power is turned off.
  • a negative voltage is applied between the control gate terminal and the substrate terminal, a positive voltage is applied between the drain and substrate terminals and the guiding gate terminal is left floating or is coupled to the ground potential.
  • the application of these voltages causes the electrons trapped in the nitride layer to tunnel through the oxide layer—due to Fowler-Nordheim tunneling—and return to the substrate 206 and/or holes to tunnel through the oxide layer and be trapped in the nitride layer to neutralize the trapped electrons.
  • the channel region positioned under the control gate has an implant doping concentration that is smaller than the implant doping concentration of the channel region positioned under the guiding gate.
  • the implant doping concentration of the channel region positioned under the control gate is greater than the doping concentration of the substrate in which the device is formed.
  • FIG. 1 is a simplified transistor schematic diagram of a non-volatile DRAM, as known in the prior art.
  • FIG. 2 is a simplified transistor schematic diagram of a non-volatile SRAM, as known in the prior art.
  • FIG. 3 is a cross-sectional view of a non-volatile memory device, in accordance with one embodiment of the present invention.
  • FIG. 4 is a cross-sectional view of a second embodiment of a non-volatile memory device, in accordance with another embodiment of the present invention.
  • FIG. 5 is an exemplary waveform of the voltages applied to various terminals of the non-volatile memory device of FIGS. 3 and 4 during a programming cycle.
  • FIG. 6 shows the effect of the increase in the threshold voltage on current conduction characteristics of non-volatile memory devices of FIGS. 3 and 4 , following a programming cycle.
  • FIG. 7 is an exemplary waveform of the voltages applied to various terminals of the non-volatile memory device of FIGS. 3 and 4 during an erase cycle.
  • FIG. 8 is an exemplary waveform of the voltages applied to various terminals of the non-volatile memory device of FIGS. 3 and 4 during a read cycle.
  • FIG. 9 is a cross-sectional view of a non-volatile memory device, in accordance with another embodiment of the present invention.
  • FIG. 10 is a cross-sectional view of a non-volatile memory device, in accordance with another embodiment of the present invention.
  • FIG. 11 shows the effect of increase in the threshold voltage on current conduction characteristics of the non-volatile memory devices of FIGS. 3 and 9 following a programming cycle.
  • an improved non-volatile memory device and method is provided.
  • the invention has been applied to a single integrated circuit device in a memory application, there can be other alternatives, variations, and modifications.
  • the invention can be applied to embedded memory applications, including those with logic or microcircuits, and the like.
  • FIG. 3 is a cross-sectional view of non-volatile memory device 200 (hereinafter alternatively referred to as device 200 ) in accordance with a first embodiment of the present invention.
  • Device 200 includes, in part, a guiding gate 220 , a control gate 230 , n-type source region 202 , n-type drain region 204 , and p-type substrate region 206 .
  • Control gate 230 which is typically formed from polysilicon, is separated from substrate layer 206 via oxide layer 208 , nitride layer 210 and oxide layer 212 .
  • control gate 230 together with oxide layer 208 , nitride layer 210 and oxide layer 212 are collectively referred to in the alternative as MNOS gate 235 .
  • Guiding gate 220 which is also typically formed from polysilicon, is separated from substrate 206 via layer 214 .
  • Layer 214 may be an oxide layer or oxinitride layer or any other dielectric layer. Guiding gate 220 partially extends over control gate 230 and is separated therefrom via oxide layer 232 .
  • oxide layer 208 has a thickness ranging from 20 ⁇ to 60 ⁇ , and each of nitride layer 210 and oxide layer 212 has a thickness ranging from 30 ⁇ to 100 ⁇ ( FIG. 3 is not drawn to scale).
  • distance L 1 may vary from, e.g., approximately 0.06 ⁇ to approximately 0.18 ⁇ ; if device 200 is manufactured using 0.25 ⁇ CMOS technology, distance L 2 may vary from, e.g., approximately 0.08 ⁇ to approximately 0.25 ⁇ .
  • Oxide layer 214 also has a thickness defined by the technology used to manufacture cell 202 .
  • oxide layer 214 may have a thickness of 70 ⁇ if 0.35 ⁇ CMOS technology is used to manufacture device 200 .
  • oxide layer 214 may have a thickness of 50 ⁇ if 0.25 ⁇ CMOS technology is used to manufacture device 200 ;
  • oxide layer 214 may have a thickness of 40 ⁇ if 0.18 ⁇ CMOS technology is used to manufacture device 200 ;
  • oxide layer 214 may have a thickness of 20 ⁇ if 0.09 ⁇ CMOS technology is used to manufacture device 200 .
  • FIG. 4 is a cross-sectional view of non-volatile memory device 300 (hereinafter alternatively referred to as device 300 ) in accordance with a second embodiment of the present invention.
  • Device 300 includes, in part, a guiding gate 320 , a control gate 330 , n-type source region 302 , n-type drain region 304 , and p-type substrate region 306 .
  • Control gate 330 which is typically formed from polysilicon, is separated from substrate layer 306 via oxide layer 308 , nitride layer 310 and oxide layer 312 .
  • control gate 330 together with oxide layer 308 , nitride layer 310 and oxide layer 312 are collectively referred to in the alternative as MNOS gate 335 .
  • Guiding gate 320 which is also typically formed from polysilicon, is separated from substrate 306 via oxide layer 314 . Guiding gate 320 partially extends over control gate 330 and is separated therefrom via oxide layer 308 , nitride layer 310 and oxide layer 312 .
  • oxide layer 308 has a thickness ranging from 20 ⁇ to 50 ⁇ , and each of nitride layer 310 and oxide layer 312 has a thickness ranging from 30 ⁇ to 100 ⁇ ( FIG. 4 is not drawn to scale).
  • distance L 3 may vary from, e.g., approximately 0.06 ⁇ to approximately 0.18 ⁇ ; if device 300 is manufactured using 0.25 ⁇ CMOS technology, distance L 4 may vary from, e.g., approximately 0.08 ⁇ to approximately 0.25 ⁇ .
  • Oxide layer 314 also has a thickness defined by the technology used to manufacture device 300 .
  • oxide layer 314 may have a thickness of 70 ⁇ if 0.35 ⁇ CMOS technology is used to manufacture device 300 .
  • oxide layer 314 may have a thickness of 50 ⁇ if 0.25 ⁇ CMOS technology is used to manufacture device 300 ;
  • oxide layer 314 may have a thickness of 40 ⁇ if 0.18 ⁇ CMOS technology is used to manufacture device 300 .
  • device 200 The programming, erase and read operations of device 200 is described below. It is understood that device 300 operates in the same manner as device 200 and thus is not discussed below.
  • a relatively high first programming voltage in the range of, e.g., 4 to 12 volts is applied between gate 230 and substrate 206
  • a second voltage in the range of, e.g., 0.5 to 1.5 volts is applied between gate 220 and substrate 206
  • a third voltage in the range of, e.g., 3 to 5 volts is applied between drain 204 and source 202 .
  • the application of these voltages causes n-type channel regions of approximate lengths L 1 and L 2 to be formed in substrate 206 (not shown).
  • FIG. 5 is an exemplary waveform of the voltages applied to various terminals of device 200 during a programming cycle, as described above.
  • FIG. 6 shows the effect of the increase in the threshold voltage of device 200 's current conduction characteristics.
  • Reference numerals 250 and 255 respectively designate the drain-current vs. gate-voltage of device before and after it is programmed.
  • the increase in the threshold voltage V th caused by trapping of the electrons i.e., the programming of non-volatile device 102
  • device 200 conducts less current when it is programmed.
  • the reduction in the current conduction capability is used to determine whether device 200 has been programmed.
  • a relatively high negative voltage e.g., ⁇ 10 volts is applied to gate 230 , approximately 0 to 1 volt is applied to drain region 204 , approximately 0 volt is applied to substrate region 206 , and guiding gate 220 is left floating or is supplied with 0 or ⁇ 1 volt.
  • the application of these voltages causes the electrons trapped in nitride layer 210 to tunnel through the oxide layer—due to Fowler-Nordheim tunneling—and return to substrate 206 and/or holes to tunnel through the oxide layer overlaying substrate 206 and be trapped in nitride layer 210 due to hot hole injection so as to neutralize the trapped electrons.
  • FIG. 7 is an exemplary waveform of the voltages applied to various terminals of device 200 during an erase cycle, as described above.
  • a second way to erase non-volatile device 200 is by injecting hot holes into nitride layer 212 .
  • substrate 206 is pulled to the Vss or a negative voltage, e.g., in the range of ⁇ 1 to ⁇ 3 volts.
  • Another voltage in the range of, e.g., 0 to ⁇ 10 volts is applied to control gate 230 .
  • Guiding gate 220 is maintained at the ground or a negative potential, e.g., ⁇ 1 to ⁇ 3 volts.
  • a positive voltage pulse of magnitude of 3 to 7.5 is applied to drain terminal 204 . Accordingly, a strong depletion region is formed between drain region 204 and substrate region 206 .
  • This depletion region causes a relatively narrow region having a high electric field across it. Therefore, band-to-band tunneling takes place causing electrons to tunnel from the surface valence band toward the conduction band, thereby generating holes. The holes so generated drift toward the substrate. Some of these holes gain sufficient energy to inject through the oxide and be trapped in the nitride layer. The injected holes neutralize any electrons that are trapped in the nitride layer, thereby causing the threshold voltage of non-volatile device 52 to return to its pre-programmed (i.e., erased) state.
  • a first voltage in the range of, e.g., 1 to 1.5 volts is applied to drain 204
  • a second voltage in the range of, e.g., 2 to 3.5 volts is applied to control gate 230
  • a third voltage in the range of, e.g., 1 to 3.5 volts is applied to guiding gate 220 .
  • the application of these voltages causes a current to flow from source 202 to drain 204 .
  • device 200 is programmed, due to its increased threshold voltage, a relatively small amount or no current flows from source 202 to drain 204 .
  • FIG. 8 is an exemplary waveform of the voltages applied to various terminals of device 200 during a read cycle, as described above.
  • FIG. 9 is a cross-sectional view of non-volatile memory device 400 (hereinafter alternatively referred to as device 400 ) in accordance with another embodiment of the present invention.
  • Device 400 is similar to device 200 except that in device 400 , channel region 410 positioned under guiding gate 220 and insulating layer 214 is implanted with p-type implants having a first doping concentration, and the channel region positioned under control gate 230 and insulating layer 208 is implanted with p-type implants having a second doping concentration.
  • Such doping causes a relatively high electric field to form in region 240 of substrate 206 to enhance the hot electron injection and further enhance the reliability of device 400 by increasing the difference in the threshold voltage of device 400 before and after programming as compared to the same threshold voltage difference for device 200 .
  • p-type substrate 206 has a doping concentration of 10 14 atoms/cm3
  • channel region 410 has a doping concentration of 10 16 atoms/cm3
  • channel region 420 has a doping concentration of 0.8 ⁇ 10 16 atoms/cm3.
  • FIG. 11 shows the current-vs-voltage characteristic of non-volatile memory devices 200 and 400 .
  • Plot 610 shows the current-vs-voltage characteristic of non-volatile memory device 400 before it is programmed or after it is erased.
  • Plot 620 shows the current-vs-voltage characteristic of non-volatile memory device 200 before it is programmed or after it is erased.
  • Plot 630 shows the current-vs-voltage characteristic of both non-volatile memory devices 200 , and 400 after they are programmed. As seen from these three plots, at any given current level, the difference between the erased and programmed voltages are greater for non-volatile memory device 400 than they are for non-volatile memory device 200 thus resulting in enhanced operational reliability.
  • FIG. 10 is a cross-sectional view of non-volatile memory device 500 (hereinafter alternatively referred to as device 500 ) in accordance with another embodiment of the present invention.
  • Device 500 is similar to device 300 except that in device 500 , channel region 510 positioned under guiding gate 320 and insulating layer 314 is implanted with p-type implants having a first doping concentration, and the channel region positioned under control gate 330 and insulating layer 308 is implanted with p-type implants having a second doping concentration.
  • Such doping causes a relatively high electric field to form in region 340 of substrate 306 to enhance the hot electron injection and further enhance the reliability of device 500 by increasing the difference in the threshold voltage of device 500 before and after programming as compared to the same threshold voltage difference for device 300 .
  • FIG. 11 described above with respect to devices 200 , 400 also applies to devices 300 , 500 .
  • p-type substrate 506 has a doping concentration of 10 14 atoms/cm3
  • channel region 410 has a doping concentration of 10 16 atoms/cm3
  • channel region 420 has a doping concentration of 0.8 ⁇ 10 16 atoms/cm3.
  • the above embodiments of the present invention are illustrative and not limitative.
  • the invention is not limited by the type of integrated circuit in which the memory device of the present invention is disposed.
  • the memory device in accordance with the present invention, may be disposed in a programmable logic device, a central processing unit, and a memory having arrays of memory cells or any other IC which is adapted to store data.

Abstract

A non-volatile memory device includes a guiding gate that extends along a first portion of the device's channel length and a control gate that extends along a second portion of the device's channel length. The first and second portions of the channel length do not overlap. The guiding gate, which overlays the substrate above the channel region, is insulated from the semiconductor substrate in which the device is formed via an oxide layer. The channel region under the guiding gate has a doping concentration greater than the doping concentration of the substrate. The remaining portion of the channel region has a doping concentration greater than the doping concentration of the substrate but less than the doping concentration of the channel region under the guiding gate. The control gate, which also overlays the substrate above the channel region, is insulated from the substrate via an oxide-nitride-oxide layer.

Description

    CROSS-REFERENCES TO RELATED APPLICATIONS
  • The present application is a continuation in-part of and claims priority under 35 U.S.C. 120 from application Ser. No. 10/394,417, filed Mar. 19, 2003, entitled “NON-VOLATILE MEMORY DEVICE”, the content of which is incorporated herein by reference in its entirety.
  • STATEMENT AS TO RIGHTS TO INVENTIONS MADE UNDER FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT
  • NOT APPLICABLE
  • REFERENCE TO A “SEQUENCE LISTING,” A TABLE, OR A COMPUTER PROGRAM LISTING APPENDIX SUBMITTED ON A COMPACT DISK.
  • NOT APPLICABLE
  • BACKGROUND OF THE INVENTION
  • The present invention relates to semiconductor integrated circuits. More particularly, the invention provides a semiconductor memory that has integrated non-volatile and dynamic random access memory cells. Although the invention has been applied to a single integrated circuit device in a memory application, there can be other alternatives, variations, and modifications. For example, the invention can be applied to embedded memory applications, including those with logic or micro circuits, and the like.
  • Semiconductor memory devices have been widely used in electronic systems to store data. There are generally two types of memories, including non-volatile and volatile memories. The volatile memory, such as a Static Random Access Memory (SRAM) or a Dynamic Random Access Memory (DRAM), loses its stored data if the power applied has been turned off. SRAMs and DRAMs often include a multitude of memory cells disposed in a two dimensional array. Due to its larger memory cell size, an SRAM is typically more expensive to manufacture than a DRAM. An SRAM typically, however, has a smaller read access time and a lower power consumption than a DRAM. Therefore, where fast access to data or low power is needed, SRAMs are often used to store the data.
  • Non-volatile semiconductor memory devices are also well known. A non-volatile semiconductor memory device, such as flash Erasable Programmable Read Only Memory (Flash EPROM), Electrically Erasable Programmable Read Only Memory (EEPROM) or, Metal Nitride Oxide Semiconductor (MNOS), retains its charge even after the power applied thereto is turned off. Therefore, where loss of data due to power failure or termination is unacceptable, a non-volatile memory is used to store the data.
  • Unfortunately, the non-volatile semiconductor memory is typically slower to operate than a volatile memory. Therefore, where fast store and retrieval of data is required, the non-volatile memory is not typically used. Furthermore, the non-volatile memory often requires a high voltage, e.g., 12 volts, to program or erase. Such high voltages may cause a number of disadvantages. The high voltage increases the power consumption and thus shortens the lifetime of the battery powering the memory. The high voltage may degrade the ability of the memory to retain its charges due to hot-electron injection. The high voltage may cause the memory cells to be over-erased during erase cycles. Cell over-erase results in faulty readout of data stored in the memory cells.
  • The growth in demand for battery-operated portable electronic devices, such as cellular phones or personal organizers, has brought to the fore the need to dispose both volatile as well as non-volatile memories within the same portable device. When disposed in the same electronic device, the volatile memory is typically loaded with data during a configuration cycle. The volatile memory thus provides fast access to the stored data. To prevent loss of data in the event of a power failure, data stored in the volatile memory is often also loaded into the non-volatile memory either during the configuration cycle, or while the power failure is in progress. After power is restored, data stored in the non-volatile memory is read and stored in the non-volatile memory for future access. Unfortunately, most of the portable electronic devices may still require at least two devices, including the non-volatile and volatile, to carry out backup operations. Two devices are often required since each of the devices often rely on different process technologies, which are often incompatible with each other.
  • To increase the battery life and reduce the cost associated with disposing both non-volatile and volatile memory devices in the same electronic device, non-volatile SRAMs and non-volatile DRAMs have been developed. Such devices have the non-volatile characteristics of non-volatile memories, i.e., retain their charge during a power-off cycle, but provide the relatively fast access times of the volatile memories. As merely an example, FIG. 1 is a transistor schematic diagram of a prior art non-volatile DRAM 10. Non-volatile DRAM 10 includes transistors 12, 14, 16 and EEPROM cell 18. The control gate and the drain of EEPROM cell 18 form the DRAM capacitor. Transistors 12 and 14 are the DRAM transistors. Transistor 16 is the mode selection transistor and thus selects between the EEPROM and the DRAM mode.
  • FIG. 2 is a transistor schematic diagram of a prior art non-volatile SRAM 40. Non-volatile SRAM 40 includes transistors 42, 44, 46, 48, 50, 52, 54, 56, resistors 58, 60 and EEPROM memory cells 62, 64. Transistors 48, 50, 52, 54 and resistors 58, 60 form a static RAM cell. Transistors 42, 44, 46, 56 are select transistors coupling EEPROM memory cells 62 and 64 to the supply voltage Vcc and the static RAM cell. Transistors 48 and 54 couple the SRAM memory cell to the true and complement bitlines BL and BL.
  • EEPROM 18 of non-volatile DRAM cell 10 (FIG. 1) and EEPROM 62, 64 of non-volatile SRAM cell 40 (FIG. 2) consume relatively large amount of current and thus shorten the battery life. Accordingly, a need continues to exist for a relatively small non-volatile memory device that, among other things, is adapted for use in a non-volatile SRAM or DRAM and consume less power than those known in the prior art.
  • While the invention is described in conjunction with the preferred embodiments, this description is not intended in any way as a limitation to the scope of the invention. Modifications, changes, and variations, which are apparent to those skilled in the art can be made in the arrangement, operation and details of construction of the invention disclosed herein without departing from the spirit and scope of the invention.
  • BRIEF SUMMARY OF THE INVENTION
  • In accordance with the present invention, a non-volatile memory device (hereinafter alternatively referred to device) includes a guiding gate that extends along a first portion of the device's channel length and a control gate that extends along a second portion of the device's channel length. The first and second portions of the channel length do not overlap. The guiding gate, which overlays the substrate above the channel region, is insulated from the semiconductor substrate in which the device is formed via an oxide layer. The control gate, which also overlays the substrate above the channel region, is insulated from the substrate via an oxide-nitride-oxide layer.
  • In some embodiment of the present invention, the thickness of the oxide layer formed above the guiding gate is greater than the thickness of the oxide layer formed above the control gate. In other embodiments, the thickness of the oxide layer formed above the control gate is greater than the thickness of the oxide layer formed above the guiding gate.
  • The device includes five terminals, namely a source terminal coupled to the device's source region, a drain terminal coupled to the device's drain region, a guiding gate terminal coupled to the device's guiding gate, a control gate terminal coupled to the device's control gate, and a substrate terminal coupled to the semiconductor substrate in which the device is formed.
  • To program the device, a first voltage is applied between the control gate terminal and the substrate terminal, a second voltage is applied between the guiding gate terminal and the substrate terminal, and a third voltage is applied between the drain and source terminals. The application of these voltages causes two non-overlapping channel regions to be formed in the substrate. Subsequently, a channel connecting the source to drain region is formed in the substrate. As the electrons drift from source to the drain due to the established electric filed, the electrons tunnel through or are injected in the oxide layer and are trapped in the nitride layer due to hot electron injection. The injected electrons remain trapped in the nitride layer even after power is turned off.
  • To erase the device after it is programmed, a negative voltage is applied between the control gate terminal and the substrate terminal, a positive voltage is applied between the drain and substrate terminals and the guiding gate terminal is left floating or is coupled to the ground potential. The application of these voltages causes the electrons trapped in the nitride layer to tunnel through the oxide layer—due to Fowler-Nordheim tunneling—and return to the substrate 206 and/or holes to tunnel through the oxide layer and be trapped in the nitride layer to neutralize the trapped electrons.
  • To read the data stored in the device, relatively small voltages are applied to each of the drain, control and guiding gates. The application of these voltages causes a current to flow from the source to the drain region. The size of this current depends on whether the device is programmed or not.
  • In some embodiments the channel region positioned under the control gate has an implant doping concentration that is smaller than the implant doping concentration of the channel region positioned under the guiding gate. The implant doping concentration of the channel region positioned under the control gate is greater than the doping concentration of the substrate in which the device is formed.
  • The accompanying drawings, which are incorporated in and form part of the specification, illustrate embodiments of the invention and, together with the description, sever to explain the principles of the invention.
  • BRIEF DESCRIPTION OF THE DRAWINGS
  • FIG. 1 is a simplified transistor schematic diagram of a non-volatile DRAM, as known in the prior art.
  • FIG. 2 is a simplified transistor schematic diagram of a non-volatile SRAM, as known in the prior art.
  • FIG. 3 is a cross-sectional view of a non-volatile memory device, in accordance with one embodiment of the present invention.
  • FIG. 4 is a cross-sectional view of a second embodiment of a non-volatile memory device, in accordance with another embodiment of the present invention.
  • FIG. 5 is an exemplary waveform of the voltages applied to various terminals of the non-volatile memory device of FIGS. 3 and 4 during a programming cycle.
  • FIG. 6 shows the effect of the increase in the threshold voltage on current conduction characteristics of non-volatile memory devices of FIGS. 3 and 4, following a programming cycle.
  • FIG. 7 is an exemplary waveform of the voltages applied to various terminals of the non-volatile memory device of FIGS. 3 and 4 during an erase cycle.
  • FIG. 8 is an exemplary waveform of the voltages applied to various terminals of the non-volatile memory device of FIGS. 3 and 4 during a read cycle.
  • FIG. 9 is a cross-sectional view of a non-volatile memory device, in accordance with another embodiment of the present invention.
  • FIG. 10 is a cross-sectional view of a non-volatile memory device, in accordance with another embodiment of the present invention.
  • FIG. 11 shows the effect of increase in the threshold voltage on current conduction characteristics of the non-volatile memory devices of FIGS. 3 and 9 following a programming cycle.
  • DETAILED DESCRIPTION OF THE INVENTION
  • According to the present invention, an improved non-volatile memory device and method is provided. Although the invention has been applied to a single integrated circuit device in a memory application, there can be other alternatives, variations, and modifications. For example, the invention can be applied to embedded memory applications, including those with logic or microcircuits, and the like.
  • FIG. 3 is a cross-sectional view of non-volatile memory device 200 (hereinafter alternatively referred to as device 200) in accordance with a first embodiment of the present invention. Device 200 includes, in part, a guiding gate 220, a control gate 230, n-type source region 202, n-type drain region 204, and p-type substrate region 206. Control gate 230, which is typically formed from polysilicon, is separated from substrate layer 206 via oxide layer 208, nitride layer 210 and oxide layer 212. In the following, control gate 230 together with oxide layer 208, nitride layer 210 and oxide layer 212 are collectively referred to in the alternative as MNOS gate 235. Guiding gate 220, which is also typically formed from polysilicon, is separated from substrate 206 via layer 214. Layer 214 may be an oxide layer or oxinitride layer or any other dielectric layer. Guiding gate 220 partially extends over control gate 230 and is separated therefrom via oxide layer 232.
  • In some embodiments, oxide layer 208 has a thickness ranging from 20 Å to 60 Å, and each of nitride layer 210 and oxide layer 212 has a thickness ranging from 30 Å to 100 Å (FIG. 3 is not drawn to scale). In these embodiments, a first portion of channel length defined between the right vertical edge of source region 202 and the right vertical edge of guiding gate 220 that is positioned above gate oxide layer 214—shown as distance L1—is the minimum distance allowed by the manufacturing technology. For example, if device 200 is manufactured using 0.18μ CMOS technology, distance L1 is also approximately 0.18μ; if device 200 is manufactured using 0.09μ CMOS technology, distance L1 is also approximately 0.09μ.
  • Furthermore, in these embodiments, a second portion of channel length defined between the left vertical edge of drain region 204 and the left vertical edge of nitride layer 210 that is positioned above gate oxide layer 208—shown as distance L2—is less than or equal to the minimum distance allowed by the manufacturing technology. For example, if device 200 is manufactured using 0.18μ CMOS technology, distance L1 may vary from, e.g., approximately 0.06μ to approximately 0.18μ; if device 200 is manufactured using 0.25μ CMOS technology, distance L2 may vary from, e.g., approximately 0.08μ to approximately 0.25μ.
  • Oxide layer 214 also has a thickness defined by the technology used to manufacture cell 202. For example, oxide layer 214 may have a thickness of 70 Å if 0.35μ CMOS technology is used to manufacture device 200. Similarly, oxide layer 214 may have a thickness of 50 Å if 0.25μ CMOS technology is used to manufacture device 200; oxide layer 214 may have a thickness of 40 Å if 0.18μ CMOS technology is used to manufacture device 200; oxide layer 214 may have a thickness of 20 Å if 0.09μ CMOS technology is used to manufacture device 200.
  • FIG. 4 is a cross-sectional view of non-volatile memory device 300 (hereinafter alternatively referred to as device 300) in accordance with a second embodiment of the present invention. Device 300 includes, in part, a guiding gate 320, a control gate 330, n-type source region 302, n-type drain region 304, and p-type substrate region 306. Control gate 330, which is typically formed from polysilicon, is separated from substrate layer 306 via oxide layer 308, nitride layer 310 and oxide layer 312. In the following, control gate 330 together with oxide layer 308, nitride layer 310 and oxide layer 312 are collectively referred to in the alternative as MNOS gate 335. Guiding gate 320, which is also typically formed from polysilicon, is separated from substrate 306 via oxide layer 314. Guiding gate 320 partially extends over control gate 330 and is separated therefrom via oxide layer 308, nitride layer 310 and oxide layer 312.
  • In some embodiments, oxide layer 308 has a thickness ranging from 20 Å to 50 Å, and each of nitride layer 310 and oxide layer 312 has a thickness ranging from 30 Å to 100 Å (FIG. 4 is not drawn to scale). In these embodiments, a first portion of channel length defined between the right vertical edge of source region 302 and the right vertical edge of guiding gate 320 that is positioned above gate oxide layer 314—shown as distance L3—is the minimum distance allowed by the manufacturing technology. For example, if device 300 is manufactured using 0.18μ CMOS technology, distance L3 is also approximately 0.18μ; if device 300 is manufactured using 0.25μ CMOS technology, distance L3 is also approximately 0.25μ.
  • Furthermore, in these embodiments, a second portion of channel length defined between the left vertical edge of drain region 304 and the left vertical edge of nitride layer 310 that is positioned above gate oxide layer 308—shown as distance L4—is less than or equal to the minimum distance allowed by the manufacturing technology. For example, if device 300 is manufactured using 0.18μ CMOS technology, distance L3 may vary from, e.g., approximately 0.06μ to approximately 0.18μ; if device 300 is manufactured using 0.25μ CMOS technology, distance L4 may vary from, e.g., approximately 0.08μ to approximately 0.25μ.
  • Oxide layer 314 also has a thickness defined by the technology used to manufacture device 300. For example, oxide layer 314 may have a thickness of 70 Å if 0.35μ CMOS technology is used to manufacture device 300. Similarly, oxide layer 314 may have a thickness of 50 Å if 0.25μ CMOS technology is used to manufacture device 300; oxide layer 314 may have a thickness of 40 Å if 0.18μ CMOS technology is used to manufacture device 300.
  • The programming, erase and read operations of device 200 is described below. It is understood that device 300 operates in the same manner as device 200 and thus is not discussed below.
  • Programming Operation
  • To program device 200, a relatively high first programming voltage in the range of, e.g., 4 to 12 volts is applied between gate 230 and substrate 206, while at the same time a second voltage in the range of, e.g., 0.5 to 1.5 volts is applied between gate 220 and substrate 206, and a third voltage in the range of, e.g., 3 to 5 volts is applied between drain 204 and source 202. The application of these voltages causes n-type channel regions of approximate lengths L1 and L2 to be formed in substrate 206 (not shown). As the electrons drift from source 202 to drain 204 due to the established electric filed (not shown), the electrons tunnel through the oxide layer overlaying substrate 206 and are trapped in nitride layer 210 due to hot electron injection. The injected electrons remain trapped in nitride layer 210 even after power is turned off. The trapped electrons, in turn, increase the threshold voltage of device 200. The relatively high electric field in region 240 of substrate 206 is so adapted as to cause the hot electron injection to occur. Subsequently, an n-type channel is also formed in region 240, thereby causing n-type to connect source 202 and drain 204. FIG. 5 is an exemplary waveform of the voltages applied to various terminals of device 200 during a programming cycle, as described above.
  • FIG. 6 shows the effect of the increase in the threshold voltage of device 200's current conduction characteristics. Reference numerals 250 and 255 respectively designate the drain-current vs. gate-voltage of device before and after it is programmed. As seen from FIG. 5, the increase in the threshold voltage Vth caused by trapping of the electrons (i.e., the programming of non-volatile device 102) reduces the drain current for each applied voltage. In other words, device 200 conducts less current when it is programmed. The reduction in the current conduction capability is used to determine whether device 200 has been programmed.
  • Erase Operation
  • To erase a programmed device, a relatively high negative voltage, e.g., −10 volts is applied to gate 230, approximately 0 to 1 volt is applied to drain region 204, approximately 0 volt is applied to substrate region 206, and guiding gate 220 is left floating or is supplied with 0 or −1 volt. The application of these voltages causes the electrons trapped in nitride layer 210 to tunnel through the oxide layer—due to Fowler-Nordheim tunneling—and return to substrate 206 and/or holes to tunnel through the oxide layer overlaying substrate 206 and be trapped in nitride layer 210 due to hot hole injection so as to neutralize the trapped electrons. The tunneling of trapped electrons back to substrate 206 and/or trapping of holes in nitride layer 210 causes the programmed non-volatile cell 102 to erase. The erase operation causes device 200's threshold to retune to its pre-programming value. FIG. 7 is an exemplary waveform of the voltages applied to various terminals of device 200 during an erase cycle, as described above.
  • A second way to erase non-volatile device 200 is by injecting hot holes into nitride layer 212. To cause hot hole injection, substrate 206 is pulled to the Vss or a negative voltage, e.g., in the range of −1 to −3 volts. Another voltage in the range of, e.g., 0 to −10 volts is applied to control gate 230. Guiding gate 220 is maintained at the ground or a negative potential, e.g., −1 to −3 volts. A positive voltage pulse of magnitude of 3 to 7.5 is applied to drain terminal 204. Accordingly, a strong depletion region is formed between drain region 204 and substrate region 206. This depletion region causes a relatively narrow region having a high electric field across it. Therefore, band-to-band tunneling takes place causing electrons to tunnel from the surface valence band toward the conduction band, thereby generating holes. The holes so generated drift toward the substrate. Some of these holes gain sufficient energy to inject through the oxide and be trapped in the nitride layer. The injected holes neutralize any electrons that are trapped in the nitride layer, thereby causing the threshold voltage of non-volatile device 52 to return to its pre-programmed (i.e., erased) state.
  • Read Operation
  • To read the data stored in non-volatile device 200, a first voltage in the range of, e.g., 1 to 1.5 volts, is applied to drain 204, a second voltage in the range of, e.g., 2 to 3.5 volts is applied to control gate 230, and a third voltage in the range of, e.g., 1 to 3.5 volts is applied to guiding gate 220. The application of these voltages causes a current to flow from source 202 to drain 204. As is known by those skilled in the art, if device 200 is programmed, due to its increased threshold voltage, a relatively small amount or no current flows from source 202 to drain 204. If device 200 is not programmed or erased, a relatively larger amount of current flows from source 202 to drain 204. A sense amplifier (not shown) senses the current that flows from source 202 and drain 204 and by sensing the size of this current determines whether device 200 is programmed or not. FIG. 8 is an exemplary waveform of the voltages applied to various terminals of device 200 during a read cycle, as described above.
  • FIG. 9 is a cross-sectional view of non-volatile memory device 400 (hereinafter alternatively referred to as device 400) in accordance with another embodiment of the present invention. Device 400 is similar to device 200 except that in device 400, channel region 410 positioned under guiding gate 220 and insulating layer 214 is implanted with p-type implants having a first doping concentration, and the channel region positioned under control gate 230 and insulating layer 208 is implanted with p-type implants having a second doping concentration. Such doping causes a relatively high electric field to form in region 240 of substrate 206 to enhance the hot electron injection and further enhance the reliability of device 400 by increasing the difference in the threshold voltage of device 400 before and after programming as compared to the same threshold voltage difference for device 200. In some embodiments, p-type substrate 206 has a doping concentration of 1014 atoms/cm3, channel region 410 has a doping concentration of 1016 atoms/cm3, and channel region 420 has a doping concentration of 0.8×1016 atoms/cm3.
  • FIG. 11 shows the current-vs-voltage characteristic of non-volatile memory devices 200 and 400. Plot 610 shows the current-vs-voltage characteristic of non-volatile memory device 400 before it is programmed or after it is erased. Plot 620 shows the current-vs-voltage characteristic of non-volatile memory device 200 before it is programmed or after it is erased. Plot 630 shows the current-vs-voltage characteristic of both non-volatile memory devices 200, and 400 after they are programmed. As seen from these three plots, at any given current level, the difference between the erased and programmed voltages are greater for non-volatile memory device 400 than they are for non-volatile memory device 200 thus resulting in enhanced operational reliability.
  • FIG. 10 is a cross-sectional view of non-volatile memory device 500 (hereinafter alternatively referred to as device 500) in accordance with another embodiment of the present invention. Device 500 is similar to device 300 except that in device 500, channel region 510 positioned under guiding gate 320 and insulating layer 314 is implanted with p-type implants having a first doping concentration, and the channel region positioned under control gate 330 and insulating layer 308 is implanted with p-type implants having a second doping concentration. Such doping causes a relatively high electric field to form in region 340 of substrate 306 to enhance the hot electron injection and further enhance the reliability of device 500 by increasing the difference in the threshold voltage of device 500 before and after programming as compared to the same threshold voltage difference for device 300. FIG. 11 described above with respect to devices 200, 400 also applies to devices 300, 500. In some embodiments, p-type substrate 506 has a doping concentration of 1014 atoms/cm3, channel region 410 has a doping concentration of 1016 atoms/cm3, and channel region 420 has a doping concentration of 0.8×1016 atoms/cm3.
  • The above embodiments of the present invention are illustrative and not limitative. The invention is not limited by the type of integrated circuit in which the memory device of the present invention is disposed. For example, the memory device, in accordance with the present invention, may be disposed in a programmable logic device, a central processing unit, and a memory having arrays of memory cells or any other IC which is adapted to store data.
  • While the invention is described in conjunction with the preferred embodiments, this description is not intended in any way as a limitation to the scope of the invention. Modifications, changes, and variations, which are apparent to those skilled in the art, can be made in the arrangement, operation and details of construction of the invention disclosed herein without departing from the spirit and scope of the invention.

Claims (17)

1. A semiconductor device comprising:
a substrate region;
a source region formed in the substrate region;
a drain region formed in the substrate region and separated from the source region by a channel region;
a first gate overlaying a first portion of the channel and separated therefrom via a first insulating layer;
a second gate overlaying a second portion of the channel and separated therefrom via a second insulating layer; wherein said first portion of the channel and said second portion of the channel do not overlap, wherein the first portion of the channel has an implant doping concentration that is greater than the implant doping concentration of a remainder portion of the channel region, wherein the remainder portion of the channel region has an implant doping concentration that is greater than the substrate doping concentration.
2. The semiconductor device of claim 1 wherein said first insulating layer is an oxide layer.
3. The semiconductor device of claim 2 wherein said second insulating layer further comprises a first oxide layer formed over said channel region, a first nitride layer formed over said first oxide layer of the second insulating layer, and a second oxide layer formed over said first nitride layer.
4. The semiconductor device of claim 3 wherein said first oxide layer of the first insulating layer is thinner than the first oxide layer of the second insulating layer.
5. The semiconductor device of claim 3 wherein said first oxide layer of the first insulating layer is thicker than the first oxide layer of the second insulating layer.
6. The semiconductor device of claim 4 wherein said first gate extends partially over the second gate.
7. The semiconductor device of claim 5 wherein said second gate extends partially over the first gate.
8. The semiconductor device of claim 6 wherein said device is programmed by applying a first voltage between the second gate and the substrate region, a second voltage between the first gate and the substrate region, and a third voltage between the source and the drain regions, said applied voltages causing electrons to be trapped in the nitride layer due to hot electron injection.
9. The semiconductor device of claim 8 wherein said electrons are trapped near the source region of the semiconductor device.
10. The semiconductor device of claim 9 wherein a channel connecting the source region to the drain region is formed in the substrate region while the device is being programmed.
11. The semiconductor device of claim 8 wherein said programmed device is erased by applying a fourth voltage to the second gate, a fifth voltage to the drain region and floating the first gate, said applied voltages causing the electrons trapped in nitride layer to tunnel to the substrate region or causing holes be trapped in the nitride layer to neutralize the trapped electrons.
12. The semiconductor device of claim 8 wherein said programmed device is erased by applying a fourth voltage to the second gate, a fifth voltage to the drain region and applying one of zero and negative voltage to the first gate, said applied voltages causing the electrons trapped in nitride layer to tunnel to the substrate region or causing holes be trapped in the nitride layer to neutralize the trapped electrons.
13. The semiconductor device of claim 7 wherein said device is programmed by applying a first voltage between the second gate and the substrate region, a second voltage between the first gate and the substrate region, and a third voltage between the source and the drain regions, said applied voltages causing electrons to be trapped in the nitride layer due to hot electron injection.
14. The semiconductor device of claim 13 wherein said electrons are trapped near the source region of the semiconductor device.
15. The semiconductor device of claim 14 wherein a channel connecting the source region to the drain region is formed in the substrate region while the device is being programmed.
16. The semiconductor device of claim 13 wherein said programmed device is erased by applying a fourth voltage to the second gate, a fifth voltage to the drain region and floating the first gate, said applied voltages causing the electrons trapped in nitride layer to tunnel to the substrate region or causing holes be trapped in the nitride layer to neutralize the trapped electrons.
17. The semiconductor device of claim 1 wherein said substrate region is a p-type region formed in a n-well region.
US11/189,548 2002-03-19 2005-07-25 Non-volatile memory device Abandoned US20060007772A1 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
US11/189,548 US20060007772A1 (en) 2002-03-19 2005-07-25 Non-volatile memory device

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
US36604602P 2002-03-19 2002-03-19
US10/394,417 US6965145B2 (en) 2002-03-19 2003-03-19 Non-volatile memory device
US11/189,548 US20060007772A1 (en) 2002-03-19 2005-07-25 Non-volatile memory device

Related Parent Applications (1)

Application Number Title Priority Date Filing Date
US10/394,417 Continuation-In-Part US6965145B2 (en) 2002-03-19 2003-03-19 Non-volatile memory device

Publications (1)

Publication Number Publication Date
US20060007772A1 true US20060007772A1 (en) 2006-01-12

Family

ID=46322313

Family Applications (1)

Application Number Title Priority Date Filing Date
US11/189,548 Abandoned US20060007772A1 (en) 2002-03-19 2005-07-25 Non-volatile memory device

Country Status (1)

Country Link
US (1) US20060007772A1 (en)

Citations (61)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4070655A (en) * 1976-11-05 1978-01-24 The United States Of America As Represented By The Secretary Of The Air Force Virtually nonvolatile static random access memory device
US4128773A (en) * 1977-11-07 1978-12-05 Hughes Aircraft Company Volatile/non-volatile logic latch circuit
US4132904A (en) * 1977-07-28 1979-01-02 Hughes Aircraft Company Volatile/non-volatile logic latch circuit
US4193128A (en) * 1978-05-31 1980-03-11 Westinghouse Electric Corp. High-density memory with non-volatile storage array
US4271487A (en) * 1979-11-13 1981-06-02 Ncr Corporation Static volatile/non-volatile ram cell
US4462090A (en) * 1978-12-14 1984-07-24 Tokyo Shibaura Denki Kabushiki Kaisha Method of operating a semiconductor memory circuit
US5051951A (en) * 1989-11-06 1991-09-24 Carnegie Mellon University Static RAM memory cell using N-channel MOS transistors
US5065362A (en) * 1989-06-02 1991-11-12 Simtek Corporation Non-volatile ram with integrated compact static ram load configuration
US5124769A (en) * 1990-03-02 1992-06-23 Nippon Telegraph And Telephone Corporation Thin film transistor
US5396461A (en) * 1992-01-16 1995-03-07 Sharp Kabushiki Kaisha Non-volatile dynamic random access memory device
US5408115A (en) * 1994-04-04 1995-04-18 Motorola Inc. Self-aligned, split-gate EEPROM device
US5590073A (en) * 1993-11-30 1996-12-31 Sony Corporation Random access memory having flash memory
US5619470A (en) * 1994-08-17 1997-04-08 Sharp Kabushiki Kaisha Non-volatile dynamic random access memory
US5646885A (en) * 1994-04-01 1997-07-08 Mitsubishi Denki Kabushiki Kaisha Fast accessible non-volatile semiconductor memory device
US5668034A (en) * 1991-12-06 1997-09-16 Intel Corporation Process for fabricating a high voltage MOS transistor for flash EEPROM applications having a uni-sided lightly doped drain
US5703388A (en) * 1996-07-19 1997-12-30 Mosel Vitelic Inc. Double-poly monos flash EEPROM cell
US5851881A (en) * 1997-10-06 1998-12-22 Taiwan Semiconductor Manufacturing Company, Ltd. Method of making monos flash memory for multi-level logic
US5914514A (en) * 1996-09-27 1999-06-22 Xilinx, Inc. Two transistor flash EPROM cell
US5946566A (en) * 1996-03-01 1999-08-31 Ace Memory, Inc. Method of making a smaller geometry high capacity stacked DRAM device
US5966601A (en) * 1997-01-21 1999-10-12 Holtek Microelectronics Inc. Method of making non-volatile semiconductor memory arrays
US5969383A (en) * 1997-06-16 1999-10-19 Motorola, Inc. Split-gate memory device and method for accessing the same
US5986932A (en) * 1997-06-30 1999-11-16 Cypress Semiconductor Corp. Non-volatile static random access memory and methods for using same
US6025265A (en) * 1995-12-22 2000-02-15 Stmicroelectronics, Inc. Method of forming a landing pad structure in an integrated circuit
US6058043A (en) * 1997-09-09 2000-05-02 Interuniversitair Micro-Elektronica Centrum Method of erasing a memory device and a method of programming a memory device for low-voltage and low-power applications
US6091634A (en) * 1997-04-11 2000-07-18 Programmable Silicon Solutions Compact nonvolatile memory using substrate hot carrier injection
US6093963A (en) * 1994-12-22 2000-07-25 Stmicroelectronics, Inc. Dual landing pad structure including dielectric pocket
US6118157A (en) * 1998-03-18 2000-09-12 National Semiconductor Corporation High voltage split gate CMOS transistors built in standard 2-poly core CMOS
US6153517A (en) * 1999-03-12 2000-11-28 Taiwan Semiconductor Manufacturing Company Low resistance poly landing pad
US6175268B1 (en) * 1997-05-19 2001-01-16 National Semiconductor Corporation MOS switch that reduces clock feedthrough in a switched capacitor circuit
US6222765B1 (en) * 2000-02-18 2001-04-24 Silicon Storage Technology, Inc. Non-volatile flip-flop circuit
US6242774B1 (en) * 1998-05-19 2001-06-05 Mosel Vitelic, Inc. Poly spacer split gate cell with extremely small cell size
US6255164B1 (en) * 1999-08-03 2001-07-03 Worldwide Semiconductor Manufacturing Corp. EPROM cell structure and a method for forming the EPROM cell structure
US6266272B1 (en) * 1999-07-30 2001-07-24 International Business Machines Corporation Partially non-volatile dynamic random access memory formed by a plurality of single transistor cells used as DRAM cells and EPROM cells
US6268246B1 (en) * 1998-09-21 2001-07-31 Texas Instruments Incorporated Method for fabricating a memory cell
US6285575B1 (en) * 1999-04-07 2001-09-04 Nec Corporation Shadow RAM cell and non-volatile memory device employing ferroelectric capacitor and control method therefor
US6352890B1 (en) * 1998-09-29 2002-03-05 Texas Instruments Incorporated Method of forming a memory cell with self-aligned contacts
US6363011B1 (en) * 1996-05-01 2002-03-26 Cypress Semiconductor Corporation Semiconductor non-volatile latch device including non-volatile elements
US6370058B1 (en) * 2000-01-21 2002-04-09 Sharp Kabushiki Kaisha Non-volatile semiconductor memory device and system LSI including the same
US6388293B1 (en) * 1999-10-12 2002-05-14 Halo Lsi Design & Device Technology, Inc. Nonvolatile memory cell, operating method of the same and nonvolatile memory array
US6414873B1 (en) * 2001-03-16 2002-07-02 Simtek Corporation nvSRAM with multiple non-volatile memory cells for each SRAM memory cell
US6426894B1 (en) * 2000-01-12 2002-07-30 Sharp Kabushiki Kaisha Method and circuit for writing data to a non-volatile semiconductor memory device
US6451643B2 (en) * 1988-11-09 2002-09-17 Hitachi, Ltd. Method of manufacturing a semiconductor device having non-volatile memory cell portion with single transistor type memory cells and peripheral portion with MISFETs
US20020146886A1 (en) * 2001-04-10 2002-10-10 Geeng-Chuan Chern Self aligned method of forming a semiconductor memory array of floating gate memory cells with vertical control gate sidewalls and insulation spacers, and a memory array made thereby
US6493262B1 (en) * 1998-05-22 2002-12-10 Winbond Electronics Corporation Method for operating nonvolatile memory cells
US6532169B1 (en) * 2001-06-26 2003-03-11 Cypress Semiconductor Corp. SONOS latch and application
US20030052361A1 (en) * 2000-06-09 2003-03-20 Chun-Mai Liu Triple self-aligned split-gate non-volatile memory device
US6556487B1 (en) * 2000-09-20 2003-04-29 Cypress Semiconductor Corp. Non-volatile static memory cell
US6573130B1 (en) * 1998-10-23 2003-06-03 Stmicroelectronics S.R.L. Process for manufacturing electronic devices having non-salicidated non-volatile memory cells, non-salicidated HV transistors, and salicidated-junction LV transistors
US6624015B2 (en) * 1998-07-22 2003-09-23 Stmicroelectronics S.R.L. Method for manufacturing electronic devices having non-volatile memory cells and LV transistors with salicided junctions
US20030198086A1 (en) * 2002-04-18 2003-10-23 Shoji Shukuri Semiconductor integrated circuit device and a method of manufacturing the same
US6654273B2 (en) * 2000-09-29 2003-11-25 Nec Electronics Corporation Shadow ram cell using a ferroelectric capacitor
US20030223288A1 (en) * 2002-03-19 2003-12-04 O2Ic, Inc. Non-volatile memory device
US6699753B2 (en) * 1998-05-22 2004-03-02 Winbond Electronics Corporation Method of fabricating an array of non-volatile memory cells
US6717203B2 (en) * 2002-07-10 2004-04-06 Altera Corporation Compact nonvolatile memory using substrate hot carrier injection
US6788573B2 (en) * 2001-08-25 2004-09-07 Woong Lim Choi Non-volatile semiconductor memory and method of operating the same
US6798008B2 (en) * 2002-03-19 2004-09-28 02Ic, Inc. Non-volatile dynamic random access memory
US6806148B1 (en) * 2002-05-28 2004-10-19 O2Ic, Inc. Method of manufacturing non-volatile memory device
US20040207025A1 (en) * 2003-04-18 2004-10-21 Renesas Technology Corp. Data processor
US6838343B2 (en) * 2003-03-11 2005-01-04 Powerchip Semiconductor Corp. Flash memory with self-aligned split gate and methods for fabricating and for operating the same
US20050136592A1 (en) * 2003-12-23 2005-06-23 02Ic, Inc. Method of manufacturing self-aligned non-volatile memory device
US20050161718A1 (en) * 2004-01-28 2005-07-28 O2Ic, Inc. Non-volatile DRAM and a method of making thereof

Patent Citations (65)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4070655A (en) * 1976-11-05 1978-01-24 The United States Of America As Represented By The Secretary Of The Air Force Virtually nonvolatile static random access memory device
US4132904A (en) * 1977-07-28 1979-01-02 Hughes Aircraft Company Volatile/non-volatile logic latch circuit
US4128773A (en) * 1977-11-07 1978-12-05 Hughes Aircraft Company Volatile/non-volatile logic latch circuit
US4193128A (en) * 1978-05-31 1980-03-11 Westinghouse Electric Corp. High-density memory with non-volatile storage array
US4462090A (en) * 1978-12-14 1984-07-24 Tokyo Shibaura Denki Kabushiki Kaisha Method of operating a semiconductor memory circuit
US4271487A (en) * 1979-11-13 1981-06-02 Ncr Corporation Static volatile/non-volatile ram cell
US6451643B2 (en) * 1988-11-09 2002-09-17 Hitachi, Ltd. Method of manufacturing a semiconductor device having non-volatile memory cell portion with single transistor type memory cells and peripheral portion with MISFETs
US5065362A (en) * 1989-06-02 1991-11-12 Simtek Corporation Non-volatile ram with integrated compact static ram load configuration
US5051951A (en) * 1989-11-06 1991-09-24 Carnegie Mellon University Static RAM memory cell using N-channel MOS transistors
US5124769A (en) * 1990-03-02 1992-06-23 Nippon Telegraph And Telephone Corporation Thin film transistor
US5668034A (en) * 1991-12-06 1997-09-16 Intel Corporation Process for fabricating a high voltage MOS transistor for flash EEPROM applications having a uni-sided lightly doped drain
US5396461A (en) * 1992-01-16 1995-03-07 Sharp Kabushiki Kaisha Non-volatile dynamic random access memory device
US5590073A (en) * 1993-11-30 1996-12-31 Sony Corporation Random access memory having flash memory
US5646885A (en) * 1994-04-01 1997-07-08 Mitsubishi Denki Kabushiki Kaisha Fast accessible non-volatile semiconductor memory device
US5408115A (en) * 1994-04-04 1995-04-18 Motorola Inc. Self-aligned, split-gate EEPROM device
US5619470A (en) * 1994-08-17 1997-04-08 Sharp Kabushiki Kaisha Non-volatile dynamic random access memory
US6093963A (en) * 1994-12-22 2000-07-25 Stmicroelectronics, Inc. Dual landing pad structure including dielectric pocket
US6025265A (en) * 1995-12-22 2000-02-15 Stmicroelectronics, Inc. Method of forming a landing pad structure in an integrated circuit
US6514819B1 (en) * 1996-03-01 2003-02-04 Ace Memory, Inc. High capacity stacked DRAM device and process for making a smaller geometry
US5946566A (en) * 1996-03-01 1999-08-31 Ace Memory, Inc. Method of making a smaller geometry high capacity stacked DRAM device
US6363011B1 (en) * 1996-05-01 2002-03-26 Cypress Semiconductor Corporation Semiconductor non-volatile latch device including non-volatile elements
US5703388A (en) * 1996-07-19 1997-12-30 Mosel Vitelic Inc. Double-poly monos flash EEPROM cell
US5914514A (en) * 1996-09-27 1999-06-22 Xilinx, Inc. Two transistor flash EPROM cell
US5966601A (en) * 1997-01-21 1999-10-12 Holtek Microelectronics Inc. Method of making non-volatile semiconductor memory arrays
US6091634A (en) * 1997-04-11 2000-07-18 Programmable Silicon Solutions Compact nonvolatile memory using substrate hot carrier injection
US6175268B1 (en) * 1997-05-19 2001-01-16 National Semiconductor Corporation MOS switch that reduces clock feedthrough in a switched capacitor circuit
US5969383A (en) * 1997-06-16 1999-10-19 Motorola, Inc. Split-gate memory device and method for accessing the same
US5986932A (en) * 1997-06-30 1999-11-16 Cypress Semiconductor Corp. Non-volatile static random access memory and methods for using same
US6058043A (en) * 1997-09-09 2000-05-02 Interuniversitair Micro-Elektronica Centrum Method of erasing a memory device and a method of programming a memory device for low-voltage and low-power applications
US6486509B1 (en) * 1997-09-09 2002-11-26 Imec Vzw Non-volatile memory cell
US5851881A (en) * 1997-10-06 1998-12-22 Taiwan Semiconductor Manufacturing Company, Ltd. Method of making monos flash memory for multi-level logic
US6118157A (en) * 1998-03-18 2000-09-12 National Semiconductor Corporation High voltage split gate CMOS transistors built in standard 2-poly core CMOS
US6242774B1 (en) * 1998-05-19 2001-06-05 Mosel Vitelic, Inc. Poly spacer split gate cell with extremely small cell size
US6493262B1 (en) * 1998-05-22 2002-12-10 Winbond Electronics Corporation Method for operating nonvolatile memory cells
US6699753B2 (en) * 1998-05-22 2004-03-02 Winbond Electronics Corporation Method of fabricating an array of non-volatile memory cells
US6624015B2 (en) * 1998-07-22 2003-09-23 Stmicroelectronics S.R.L. Method for manufacturing electronic devices having non-volatile memory cells and LV transistors with salicided junctions
US6268246B1 (en) * 1998-09-21 2001-07-31 Texas Instruments Incorporated Method for fabricating a memory cell
US6352890B1 (en) * 1998-09-29 2002-03-05 Texas Instruments Incorporated Method of forming a memory cell with self-aligned contacts
US6573130B1 (en) * 1998-10-23 2003-06-03 Stmicroelectronics S.R.L. Process for manufacturing electronic devices having non-salicidated non-volatile memory cells, non-salicidated HV transistors, and salicidated-junction LV transistors
US6153517A (en) * 1999-03-12 2000-11-28 Taiwan Semiconductor Manufacturing Company Low resistance poly landing pad
US6285575B1 (en) * 1999-04-07 2001-09-04 Nec Corporation Shadow RAM cell and non-volatile memory device employing ferroelectric capacitor and control method therefor
US6266272B1 (en) * 1999-07-30 2001-07-24 International Business Machines Corporation Partially non-volatile dynamic random access memory formed by a plurality of single transistor cells used as DRAM cells and EPROM cells
US6255164B1 (en) * 1999-08-03 2001-07-03 Worldwide Semiconductor Manufacturing Corp. EPROM cell structure and a method for forming the EPROM cell structure
US6388293B1 (en) * 1999-10-12 2002-05-14 Halo Lsi Design & Device Technology, Inc. Nonvolatile memory cell, operating method of the same and nonvolatile memory array
US6426894B1 (en) * 2000-01-12 2002-07-30 Sharp Kabushiki Kaisha Method and circuit for writing data to a non-volatile semiconductor memory device
US6370058B1 (en) * 2000-01-21 2002-04-09 Sharp Kabushiki Kaisha Non-volatile semiconductor memory device and system LSI including the same
US6222765B1 (en) * 2000-02-18 2001-04-24 Silicon Storage Technology, Inc. Non-volatile flip-flop circuit
US20030052361A1 (en) * 2000-06-09 2003-03-20 Chun-Mai Liu Triple self-aligned split-gate non-volatile memory device
US6556487B1 (en) * 2000-09-20 2003-04-29 Cypress Semiconductor Corp. Non-volatile static memory cell
US6654273B2 (en) * 2000-09-29 2003-11-25 Nec Electronics Corporation Shadow ram cell using a ferroelectric capacitor
US6414873B1 (en) * 2001-03-16 2002-07-02 Simtek Corporation nvSRAM with multiple non-volatile memory cells for each SRAM memory cell
US20020146886A1 (en) * 2001-04-10 2002-10-10 Geeng-Chuan Chern Self aligned method of forming a semiconductor memory array of floating gate memory cells with vertical control gate sidewalls and insulation spacers, and a memory array made thereby
US6532169B1 (en) * 2001-06-26 2003-03-11 Cypress Semiconductor Corp. SONOS latch and application
US6788573B2 (en) * 2001-08-25 2004-09-07 Woong Lim Choi Non-volatile semiconductor memory and method of operating the same
US20030223288A1 (en) * 2002-03-19 2003-12-04 O2Ic, Inc. Non-volatile memory device
US6798008B2 (en) * 2002-03-19 2004-09-28 02Ic, Inc. Non-volatile dynamic random access memory
US6965145B2 (en) * 2002-03-19 2005-11-15 O2Ic, Inc. Non-volatile memory device
US20030198086A1 (en) * 2002-04-18 2003-10-23 Shoji Shukuri Semiconductor integrated circuit device and a method of manufacturing the same
US6806148B1 (en) * 2002-05-28 2004-10-19 O2Ic, Inc. Method of manufacturing non-volatile memory device
US6717203B2 (en) * 2002-07-10 2004-04-06 Altera Corporation Compact nonvolatile memory using substrate hot carrier injection
US6838343B2 (en) * 2003-03-11 2005-01-04 Powerchip Semiconductor Corp. Flash memory with self-aligned split gate and methods for fabricating and for operating the same
US20040207025A1 (en) * 2003-04-18 2004-10-21 Renesas Technology Corp. Data processor
US20050136592A1 (en) * 2003-12-23 2005-06-23 02Ic, Inc. Method of manufacturing self-aligned non-volatile memory device
US6972229B2 (en) * 2003-12-23 2005-12-06 02Ic, Inc. Method of manufacturing self-aligned non-volatile memory device
US20050161718A1 (en) * 2004-01-28 2005-07-28 O2Ic, Inc. Non-volatile DRAM and a method of making thereof

Similar Documents

Publication Publication Date Title
US6954377B2 (en) Non-volatile differential dynamic random access memory
US6671209B2 (en) Erasing method for p-channel NROM
US6965145B2 (en) Non-volatile memory device
US4958321A (en) One transistor flash EPROM cell
US6841821B2 (en) Non-volatile memory cell fabricated with slight modification to a conventional logic process and methods of operating same
US5896315A (en) Nonvolatile memory
US5295107A (en) Method of erasing data stored in flash type nonvolatile memory cell
US6457108B1 (en) Method of operating a system-on-a-chip including entering a standby state in a non-volatile memory while operating the system-on-a-chip from a volatile memory
US7515479B2 (en) Nonvolatile semiconductor storage device and method for writing therein
US6798008B2 (en) Non-volatile dynamic random access memory
US6026017A (en) Compact nonvolatile memory
KR100219331B1 (en) Non-volatile semiconductor memory device and method for eraser and production thereof
US6493262B1 (en) Method for operating nonvolatile memory cells
US6965524B2 (en) Non-volatile static random access memory
US7342833B2 (en) Nonvolatile memory cell programming
JP3914340B2 (en) Flash memory device
US5576995A (en) Method for rewriting a flash memory
US7088623B2 (en) Non-volatile memory technology suitable for flash and byte operation application
US20030190771A1 (en) Integrated ram and non-volatile memory cell method and structure
US20060007772A1 (en) Non-volatile memory device
US20050219913A1 (en) Non-volatile memory array
US7106629B2 (en) Split-gate P-channel flash memory cell with programming by band-to-band hot electron method
US6711065B2 (en) 1 T flash memory recovery scheme for over-erasure
US20030213991A1 (en) Flash memory cell
JPH07192486A (en) Programming method of electrically programmable read-only memory cell

Legal Events

Date Code Title Description
AS Assignment

Owner name: O2IC, INC., CALIFORNIA

Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNOR:CHOI, KYU HYUN;REEL/FRAME:016528/0851

Effective date: 20050823

STCB Information on status: application discontinuation

Free format text: ABANDONED -- FAILURE TO RESPOND TO AN OFFICE ACTION